MARIA MARGARETTE COLUMNA
STEM II ZARA
1. WHAT HAPPENS DURING PRE-EMBRYONIC AND EMBRYONIC DEVELOPMENT?
 The pre-embryonic period, known as the germinal phase, is the first and shortest
phase embryonic development. It last from fertilization to the second week of to
the second week of the embryo’s life. In this phase of embryo development, the
zygote repeatedly self-replicates. Starting in the second week after fertilization,
the embryo starts to develop distinct cell layers, form the nervous system, make
blood cells, and form many organs.
2. WHAT ARE THE MAJOR EVENTS DURING FERTILIZATION?
 Sperm preparation
 Sperm- egg recognition
 Binding
 Fusion of sperm and pro-nuclei and activation of zygote
3. HOW DOES THE DEVELOPMENT OF THE GENITALS DIFFER IN MALES AND
FEMALES?
 Both sexes develop urogenital and anal membranes early in sexual
differentiation. Under the influence of androgens ,mostly DHT, the male tissues
will enlarge and fuse to create the penis and the scrotum. In comparison, the
female tissues will develop into the female genitals in the absence of androgens.
Male genitals development.
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Scrotum and testes grow larger
Penis becomes longer and seminal vesicles and prostate gland grow
Hair begins to grow in the public area and later on the face and underarms
Ejaculation becomes possible(usually in mid adolescene around 12-14 years old)
Female genitals development
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Hair begins to grow in the public area and later on the underarms
Maturation of the breast ,ovaries, uterus, and vagina
Start of menstruation